What's the noun for ontology? Here's the word you're looking for.
ontology
(philosophy) The branch of metaphysics that addresses the nature or essential characteristics of being and of things that exist; the study of being qua being.
(philosophy) The theory of a particular philosopher or school of thought concerning the fundamental types of entity in the universe.
(logic) A logical system involving theory of classes, developed by Stanislaw Lesniewski (1886-1939).
(computer science, information science) A structure of concepts or entities within a domain, organized by relationships; a system model.